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/*
* Luby-Rackoff
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/lubyrack.h>
#include <botan/internal/xor_buf.h>
namespace Botan {
/*
* Luby-Rackoff Encryption
*/
void LubyRackoff::encrypt_n(const byte in[], byte out[], size_t blocks) const
{
const size_t len = hash->output_length();
secure_vector<byte> buffer_vec(len);
byte* buffer = &buffer_vec[0];
for(size_t i = 0; i != blocks; ++i)
{
hash->update(K1);
hash->update(in, len);
hash->final(buffer);
xor_buf(out + len, in + len, buffer, len);
hash->update(K2);
hash->update(out + len, len);
hash->final(buffer);
xor_buf(out, in, buffer, len);
hash->update(K1);
hash->update(out, len);
hash->final(buffer);
xor_buf(out + len, buffer, len);
hash->update(K2);
hash->update(out + len, len);
hash->final(buffer);
xor_buf(out, buffer, len);
in += 2 * len;
out += 2 * len;
}
}
/*
* Luby-Rackoff Decryption
*/
void LubyRackoff::decrypt_n(const byte in[], byte out[], size_t blocks) const
{
const size_t len = hash->output_length();
secure_vector<byte> buffer_vec(len);
byte* buffer = &buffer_vec[0];
for(size_t i = 0; i != blocks; ++i)
{
hash->update(K2);
hash->update(in + len, len);
hash->final(buffer);
xor_buf(out, in, buffer, len);
hash->update(K1);
hash->update(out, len);
hash->final(buffer);
xor_buf(out + len, in + len, buffer, len);
hash->update(K2);
hash->update(out + len, len);
hash->final(buffer);
xor_buf(out, buffer, len);
hash->update(K1);
hash->update(out, len);
hash->final(buffer);
xor_buf(out + len, buffer, len);
in += 2 * len;
out += 2 * len;
}
}
/*
* Luby-Rackoff Key Schedule
*/
void LubyRackoff::key_schedule(const byte key[], size_t length)
{
K1.assign(key, key + (length / 2));
K2.assign(key + (length / 2), key + length);
}
/*
* Clear memory of sensitive data
*/
void LubyRackoff::clear()
{
zap(K1);
zap(K2);
hash->clear();
}
/*
* Return a clone of this object
*/
BlockCipher* LubyRackoff::clone() const
{
return new LubyRackoff(hash->clone());
}
/*
* Return the name of this type
*/
std::string LubyRackoff::name() const
{
return "Luby-Rackoff(" + hash->name() + ")";
}
/*
* Luby-Rackoff Constructor
*/
LubyRackoff::LubyRackoff(HashFunction* h) : hash(h)
{
}
}
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